Stuck on what to do with an illegal splice I found

I was running a new line in an old apartment building yesterday. Behind a panel, I spotted a messy splice that was clearly not up to code. It looked like someone had tapped into the main feed without permission. My first thought was to fix it right away, but the tenant asked me to leave it alone. They said the landlord would charge them for the repair. Now I'm stuck between doing the right thing and keeping the customer happy. If I report it, the tenant could get in trouble. If I ignore it, I'm breaking rules myself. It's a no-win situation that has me stressed out.